Quercus Alba was the Ambassador of Allebahst in the United States and a witness in a double murder in the embassies of Allebahst and Babahl. For more than ten years, he served the country of Cohdopia and then Allebahst as their foreign ambassador to the United States. However, this was all a front to his true identity: the leader of an international criminal organization that specialized in counterfeiting and smuggling contraband.

Quercus Alba was originally a general who led Cohdopia through many successful wars. He was considered a hero in his homeland, as he saved the royal family of Codophia from danger countless times. He was thus eventually given the important position of the Cohdopian ambassador to the United States. However, his power eventually corrupted him and he became the leader of an international smuggling ring, using his position and influence over the Cohdopian court system to become legally virtually impregnable. He took on the appearance of a feeble old man who blamed himself for everything that went wrong in his embassy, so that no one ever suspected him of any real wrongdoing. Alba also acquired the assistance of the Amano Group, which used its vast international connections to accelerate the ring's infectious activities.

In 2008 or 2009, Cece Yew, an employee at the Amano Group, went to the police with incriminating evidence against her employer, so Alba ordered Manny Coachen to kill her. Coachen did so but was captured by the police soon afterward. Coachen was spared a conviction thanks to the efforts of Ernest Amano, who had some of his henchmen steal the security footage at Cece's apartment that would have incriminated Coachen (as well as Alba, as it would turn out ten years later). In the wake of the trial, Alba sent in one of his agents to pose as Cece's mourning sister "Calisto" and keep an eye on the related parties.

Byrne Faraday and Tyrell Badd, the prosecutor and lead detective in the trial, were determined to take down the smuggling organization and expose its leader. "Calisto" was able to position herself within the group, and the three became the Great Thief Yatagarasu. Alba allowed the Yatagarasu to expose his allied companies, all the while trusting "Calisto" to keep them from reaching their ultimate goal.

Three years later, Faraday broke into the Cohdopian Embassy and stole what would later be known as the Yatagarasu's Key, and in retaliation Alba ordered "Calisto" to take him out. Meanwhile, another witness threatened to expose Alba's criminal dealings, a Cohdopian embassy employee named Deid Mann. "Calisto" devised and executed a plan to kill both individuals and retrieve the key, which effectively nullified all remaining threats to Alba at the time. Thus, for the next seven years, Alba continued his malicious activities unopposed. During that time, Cohdopia succumbed to civil war and was split into two countries, Allebahst and Babahl. The Cohdopian Embassy subsequently divided itself symmetrically with each country controlling one half of the property, and Manny Coachen became the assistant to Babahlese ambassador Colias Palaeno. Meanwhile, Alba planted his spy on Interpol as a mysterious woman named Shih-na.

In 2019, Manny Coachen organized a goodwill event between Allebahst and Babahl. As a part of this event, two identical-looking statues, one from each country, would be tested to see which country owned the real Primidux Statue. This would determine which country would have more sway over matters related to a possible reunification. Both Alba and Coachen already knew that Allebahst's statue was the real one because the fake one was being used to store plates for making counterfeit bills in Zheng Fa. Seeking to usurp Alba, Coachen hired a thief, Ka-Shi Nou, to switch the two statues so that Palaeno would become the ambassador of a reunited Cohdopia.

Alba, however, found out about Coachen's treachery. Thus, he devised a plan with Shih-na to have Coachen killed and blame the death on the Yatagarasu. The story would be that the Yatagarasu had returned to the embassy to finish the leader of the smuggling ring once and for all. To this end, Alba sent a Yatagarasu calling card to the media, warning that the Yatagarasu would steal the embassy's dirtiest secrets. This brought the Interpol group containing Shih-na to the embassy as security detail, setting Shih-na up for the events that would unfold.

Near the end of a special Steel Samurai show in the Theatrum Neutralis, Alba confronted Coachen in the dressing room of the stage and attacked him with an ornamental knife from his office. Coachen managed to stab Alba with the Yatagarasu's Key before Alba delivered a fatal blow to the neck. A prop pushcart containing boxes of Samurai Dogs was in the room; Alba removed some of the boxes and stowed the body inside. Ensuring that no evidence was left behind, Alba hid the key inside a bouquet of flowers and quickly returned to his seat. He then participated in a scheduled photo op with Palaeno and the Steel Samurai, holding the bouquet containing the murder weapon. The Steel Samurai then carried the pushcart back into Allebahst, oblivious to the body inside, and then Alba followed. Alba was scheduled to give a speech in the rose garden at Allebahst, so he kept the body in his office in the meantime.

Now the body had to be transported to Babahl. Alba arranged two statues in the rose garden so that when the spotlights shone onto the podium on which he was to speak, the shadows of the statues would form that of the Yatagarasu. This threw all of the attendants into a panic, and eventually the garden was emptied. The pool in the garden was connected to another one in the open-air stage in Babahl; Alba pushed the pushcart into the garden pool while Shih-na started a fire in Babahl and jumped into the pool, causing all of the water in both pools to be used for the ensuing firefighting effort. Shih-na then collected the body while Alba refilled the pools so that Shih-na could make it back to land. The transport went off without a hitch.

Alba then arranged to retrieve the counterfeiting plates. He invited prosecutor Franziska von Karma, who was part of the security in Allebahst, into his office to talk, to create a possible scapegoat. After von Karma left, Alba took two of the support sticks for his passionflowers, wrapped a long, sturdy wire around a ceiling fan, and shot the ends of the wire with a crossbow to the Babahlese secretariat's office using the support sticks as crossbow bolts. Shih-na then completed the loop with a ceiling fan on her end and the two statues were switched using the wire loop, powered by the two fans. Finally, when Ka-Shi Nou barged into the office to steal the real statue, Alba attacked and killed him with the fake statue. He then stained a pair of bonsai trimming shears with his own blood to make it seem as though Nou had attacked him, so that he could plead justified self-defense in the Allebahstian courts, if it ever came to that.

Quercus Alba and Miles Edgeworth first crossed paths when Alba interrupted an argument between Edgeworth and Interpol agent Shi-Long Lang about access to investigate the Allebahstian side of the embassy. At first, Alba refused to allow Edgeworth permission, but Palaeno convinced him to change his mind. Some time later, just as Edgeworth and Lang felt that they were getting close to the truth, Alba appeared to tell them to hold off the investigation. Desperately, Lang accused Franziska von Karma, forcing Alba to let the group investigate his office for evidence. Edgeworth thus came to uncover the statue-switching operation and to name Alba as the smuggling ring's leader and Nou's killer.

To prove that Alba was involved in the KG-8 Incident, Edgeworth showed him the video from the KG-8 Incident that the Amano Group had stolen, which showed Alba inside a Cohdopian governmental car, wearing his unique medal. While this was happening, Alba laughed and dropped his frail old man façade, straightening up to his full height. He smugly pointed out that he had a right to be tried in his own country because of his ambassadorship as well as the fact that the murder had occurred on Allebahstian soil. As a show of his legal power over Edgeworth, Alba gave his self-defense plea for the murder, showing Edgeworth his wound, and then left to fetch eviction papers for the entire investigation team.

Edgeworth refused to leave because the Theatrum Neutralis was considered American soil, so Alba had no power to kick any of them out. Alba told them that he was about to catch a flight back to Allebahst, and that Edgeworth had no authority to stop him. However, Edgeworth was not alone, and several people came to his aid, taking their chance to stop the leader of the smuggling ring. Through Palaeno's and Kay Faraday's persuasive efforts, Alba was delayed enough for Edgeworth to establish his motive and the location of the murder weapon. During this time, Lang contacted the Allebahstian imperial household and secured the removal of Alba's ambassadorship. Through the investigative efforts of Dick Gumshoe, Larry Butz and Wendy Oldbag, Edgeworth figured out the method of transport of the body after the murder, including the smuggling route and Shih-na's involvement.

Alba then tried to convince Edgeworth that he had been watching the Steel Samurai show the entire time, but his story fell flat when he misremembered one of the details, inadvertently revealing the real crime scene. Out of the blue, Oldbag gave Edgeworth a box of Samurai Dogs, which was found to have a single drop of Alba's blood, which Alba had completely overlooked, placing him inside the dressing room. Finally, the only weapon that he could have brought into the room was the Yatagarasu's Key. Alba lamented his defeat and, knowing that he would now be tried in America for Coachen's murder, was reduced to a form meaner than his original façade.

On March 17, 2019, Quercus Alba stood trial in an American courtroom for the murder of Manny Coachen in the Theatrum Neutralis, which was considered American soil. Alba was now helpless as prosecutor Miles Edgeworth revealed all of the terrible deeds that he had committed, which had led to the murder. Alba was compelled to release information to assist Interpol in flushing out the rest of the smuggling ring, finally ridding Zheng Fa of the counterfeiting operation that had been plaguing its economy. A week later, Alba stood trial in a courtroom in the newly reunited Cohdopia for the murder of Ka-Shi Nou, unable even to plead justified self-defense now and at the mercy of prosecutor Franziska von Karma. Thus, Alba was finally convicted of his crimes.

These "crimes" you all speak so seriously of... To me, this has all been nothing more than a game. You may chase me out of this embassy with your accusations... but it's no big deal. Allebahst has numerous other embassies in other countries around the world. All you would accomplish is you would change the backdrop of our little game!

On the surface, Ambassador Alba appeared to be a hunched, frail old man who was mostly agreeable but often blamed himself when things went wrong. This was a façade, however, as he was perfectly capable of standing up straight, and in actuality he was a cold, ruthless, arrogant man. As a politician, he was quite learned in the art of giving vague testimonies that didn't really answer anything, as well as giving every excuse possible to get out of a jam. This made Alba an extremely stubborn and frustrating opponent in arguments. To compound this, he was also extremely egotistical, taunting everyone who opposed him at every available opportunity.

Alba was exceedingly selfish and greedy. He saw other human lives as mere pawns for him to use in his "game". This included the smuggling ring itself, as it seems that he cared not even for his underlings, throwing them away to the Yatagarasu to protect himself. Even his testimonies were centered around him, avoiding mentions of other people if he could help it. Everything he did was directly for his benefit. Ironically, this served as his downfall as he accumulated many enemies, even within his own ranks.

Alba's self-serving personality was matched only by his sheer determination. Apart from his innumerable excuses and failsafes, he was able to keep up his tame alter-ego for the whole duration of his leadership of the smuggling ring. Even after he was unmasked, he was able to hide all semblance of fear and anxiety, displaying only arrogance and overconfidence throughout the ordeal between him and Miles Edgeworth.

His Japanese name, "Carnage Onred" (カーネイジオンレッド), may be a play on "red carnation", following the floral theme of his country. Alternatively, it could be a play on "Carnage on red", with "carnage" meaning death and destruction and "red" referring to the color of blood, or his victim Ka-Shi Nou whose Japanese name contains the kanji for "red" (赤).

His English name, "Quercus Alba", is the scientific name for the White Oak. This may be a reference to his appearance, as he looks very much like an old tree; his hair looks like the leaves of an oak, his long nose resembles a tree branch, his wrinkled skin bears some resemblance to tree bark and his beard looks like the roots of a tree. The name may also be a reference to his age as oak trees can live for hundreds of years, or simply following the floral theme of Allebahst. In fact, there is a small tree in the corner of Alba's office that bears a striking resemblance to the man.

Quercus Alba was designed to be the secret mastermind behind most of the events in Ace Attorney Investigations: Miles Edgeworth. All of the killers in the game have some connection to his smuggling ring, and all but one are directly employed into it. To signify his importance further, he has his own vocalized "Objection!" despite not being an attorney, the first time this has happened in the series.

When Alba is defeated he says "And I would've gotten away with it too if it wasn't for you meddling prosecutors!". This is a paraphrase of the "I would have gotten away with it too if it wasn't for those meddling kids!" catchphrase commonly spoken by the culprit at the resolution of most Scooby-Doo cases.

When Shi-Long Lang revokes Alba's diplomatic immunity, he remarks that "Your diplomatic immunity has just been revoked." This is similar to the famous exchange at the end of the action comedy film Lethal Weapon 2 between protagonist Roger Murtaugh and antagonist Arjen Rudd, where the latter boasts of his diplomatic immunity only to get shot by Murtaugh, who then quips "It's just been revoked."